Instrument Control (GPIB, Serial, VISA, IVI)

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NI 9871 Bias Resistors

Yes it was set at 9600 baud.


I assume you don't put the 390 ohm resistor between the Vcc of 24v for the module and the Tx/Rx+ line? That would bring the Tx/Rx+ line too high?


The other device is an Adam 4570 RS485-->Ethernet converter.

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Message 11 of 17

No, Vcc is 5V (or 3.3V) the power voltage of the RS-485 transceiver IC.


Is the data at the video from both devices ?

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Message 12 of 17

Without opening the module and modifying it I won't be able to fit that resistor, which I why I'm confused, surely the module should already have those fitted to conform the the spec?


The data in the video is just the 9871 sending. The adam module sent this..


I didn't video it as it didnt change.

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Message 13 of 17

How did you connect the scope ? Tx/Rx+ and 0V ?

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Message 14 of 17

Between Tx/Rx+ and Tx/Rx-

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Message 15 of 17


Did you solve the issue? If so - how?

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Message 16 of 17

This thread is 10 years old !!

I think it is better to create a new thread and describe your problem with enough information.



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Message 17 of 17